Improvement in scroll-saws



UNITED STATES WILLIAM H. DOANE, OF CINCINNATI,

OHIO, ASSIGNOR TO J. A. FAY 85 CO.,

OF SAME PLACE.

IMPROVEMENT IN SCROLL-SAW-S.

Specification forming part of Letters Patent No. 134,650, dated January 7, 1373.

To all whom it may concern:

Bc it known that I, WILLIAM HOWARD DOANE, of Cincinnati, Hamilton county, Ohio, have invented a new and useful Improvement in Scroll-Saws, of which the following is a specification z This is a device for maintaining the proper tension of the saw-blade of a scroll-sawing machine; and comprises a spring or cushion, preferably of India rubber and cylindrical in form, inclosedbetwecn suitable heads, of which one, bein gixed, constitutes an abutment,while the other head, being movable, communicates the resilient property of the spring, through the medium of a stem, whose hooked upper extremity occupies a cavity near the axis of a segmental pulley, with Whose arc or tire the saw-blade is connected by the custom ary strap. The bearing-point or shoulder of said cavity is located as near as possible to the axis or l center of oscillation of the segment-pulley, in

order that a very slight compression of the spring may correspond with a full stroke of the General Description.

Figure 1 is a vertical section of my tension device in the normal or elevated position of the saw-blade. Fig. 2 is a partially-sectionized elevation of the same parts, the saw-blade being at the limit of its downward stroke. Fig. 3 is an enlarged vertical section of the segment-pulleys fulcrum. Fig. et is an enlarged transverse section in the line :v m of Fig. 1, looking rearward.

A is a portion of the supporting-frame or stanchion, the same having iianges B and a vertical slot, C, for the attaching-screw D of a guard or housing, E, of the represented approximately U form. The housing E has,near

its upper part, ears F, which being perforated, as shown, serve as the journal-bearings of the journals G of a segment-pulley, H, to whose tire or arc the saw-blade is connected by means of the customary steel or leather strap, and to accommodate which pulley the said housing is slotted at e. A cavity, I, in the pulleys hub receives the hooked upper extremity of a vertical rod or stem, J, which, traversing freely a notch, k, in lug K and upper (stationary) head L and perforated cylindrical rubber spring or cushion M, is screwed into lower (adjustable and movable) head N of said cushion, whence it passes freely down through guide-hole e in the lower part of the housing E.

The above-described preferred form of my devices may be varied in non-essential particulars. For example, the spring M may be located above instead of below the segment-pulley and act by a pushing instead of the represented pulling force.

A spiral or helical spring may he used in stead of the rubber cylinder.

Two or more attaching-screws in connection with guideanges'may replace the single atcaching-screw and vertical slot.

Operation.

The lower head N being screwed down or slackened, the housing E is raised or lowered to the proper point for engagement of the strap with the saw-blade, and secured in this position by means of the screw D. The head N is then screwed up until the proper tension is obtained, and the machine is then ready for work.

The above-described arrangement and relation of parts enabling the employment of a powerful spring or cushion subjected to very slight compression, such spring is thereby rendered practically everlasting as to its resilient properties.

It will be seen that all the operative parts G H L M N of my saw-straining device are contained within the housing E andthe recessed or. anged and slotted lstanchion A, these parts being arranged and operated in the smallest `practicable space, and no part of them projecting beyond these two members.

My machine is capable of being run at the highest speed without trembling or vibration,

and consequently so as to sew smoothly and with the recessed and slotted stanehion A and equally without loss of power.

Claims.

I claim herein as new and of my inventionl. The segment-pulley recessed rock-shaft G, in combination with the spring M and its attuehments, when constructed and operated in the manner and for the purpose shown and described.

2. The herein-described housing E, combined containing the entire saw-straining devices G H L M N, in the' manner and for the purpose set forth.

In testimonr of which invention I hereunto set my hand.

f W. H. DOANE.

Attest GEO. H. KNIGHT, JAMEs H. LAYMAN.' 

